* sys/netinet6/in6.h: check parameter type to IN6_ARE_ADDR_EQUAL().   this should avoid typecast bugs like below.
* sys/netinet6/in6.h: check parameter type to IN6_ARE_ADDR_EQUAL().
  this should avoid typecast bugs like below.

MarginC/kame,MarginC/kame,MarginC/kame,MarginC/kame,MarginC/kame,MarginC/kame,MarginC/kame